| 1 | /* vi: set sw=4 ts=4: */
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| 2 | /* Licensed under GPLv2 or later, see file LICENSE in this source tree.
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| 3 | *
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| 4 | * FIXME:
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| 5 | * In privileged mode if uname and gname map to a uid and gid then use the
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| 6 | * mapped value instead of the uid/gid values in tar header
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| 7 | *
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| 8 | * References:
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| 9 | * GNU tar and star man pages,
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| 10 | * Opengroup's ustar interchange format,
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| 11 | * http://www.opengroup.org/onlinepubs/007904975/utilities/pax.html
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| 12 | */
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| 13 |
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| 14 | #include "libbb.h"
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| 15 | #include "bb_archive.h"
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| 16 |
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| 17 | typedef uint32_t aliased_uint32_t FIX_ALIASING;
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| 18 | typedef off_t aliased_off_t FIX_ALIASING;
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| 19 |
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| 20 | /* NB: _DESTROYS_ str[len] character! */
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| 21 | static unsigned long long getOctal(char *str, int len)
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| 22 | {
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| 23 | unsigned long long v;
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| 24 | char *end;
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| 25 | /* NB: leading spaces are allowed. Using strtoull to handle that.
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| 26 | * The downside is that we accept e.g. "-123" too :(
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| 27 | */
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| 28 | str[len] = '\0';
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| 29 | v = strtoull(str, &end, 8);
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| 30 | /* std: "Each numeric field is terminated by one or more
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| 31 | * <space> or NUL characters". We must support ' '! */
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| 32 | if (*end != '\0' && *end != ' ') {
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| 33 | int8_t first = str[0];
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| 34 | if (!(first & 0x80))
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| 35 | bb_error_msg_and_die("corrupted octal value in tar header");
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| 36 | /*
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| 37 | * GNU tar uses "base-256 encoding" for very large numbers.
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| 38 | * Encoding is binary, with highest bit always set as a marker
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| 39 | * and sign in next-highest bit:
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| 40 | * 80 00 .. 00 - zero
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| 41 | * bf ff .. ff - largest positive number
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| 42 | * ff ff .. ff - minus 1
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| 43 | * c0 00 .. 00 - smallest negative number
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| 44 | *
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| 45 | * Example of tar file with 8914993153 (0x213600001) byte file.
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| 46 | * Field starts at offset 7c:
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| 47 | * 00070 30 30 30 00 30 30 30 30 30 30 30 00 80 00 00 00 |000.0000000.....|
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| 48 | * 00080 00 00 00 02 13 60 00 01 31 31 31 32 30 33 33 36 |.....`..11120336|
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| 49 | *
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| 50 | * NB: tarballs with NEGATIVE unix times encoded that way were seen!
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| 51 | */
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| 52 | /* Sign-extend 7bit 'first' to 64bit 'v' (that is, using 6th bit as sign): */
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| 53 | first <<= 1;
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| 54 | first >>= 1; /* now 7th bit = 6th bit */
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| 55 | v = first; /* sign-extend 8 bits to 64 */
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| 56 | while (--len != 0)
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| 57 | v = (v << 8) + (uint8_t) *++str;
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| 58 | }
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| 59 | return v;
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| 60 | }
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| 61 | #define GET_OCTAL(a) getOctal((a), sizeof(a))
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| 62 |
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| 63 | #define TAR_EXTD (ENABLE_FEATURE_TAR_GNU_EXTENSIONS || ENABLE_FEATURE_TAR_SELINUX)
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| 64 | #if !TAR_EXTD
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| 65 | #define process_pax_hdr(archive_handle, sz, global) \
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| 66 | process_pax_hdr(archive_handle, sz)
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| 67 | #endif
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| 68 | /* "global" is 0 or 1 */
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| 69 | static void process_pax_hdr(archive_handle_t *archive_handle, unsigned sz, int global)
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| 70 | {
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| 71 | #if !TAR_EXTD
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| 72 | unsigned blk_sz = (sz + 511) & (~511);
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| 73 | seek_by_read(archive_handle->src_fd, blk_sz);
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| 74 | #else
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| 75 | unsigned blk_sz = (sz + 511) & (~511);
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| 76 | char *buf, *p;
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| 77 |
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| 78 | p = buf = xmalloc(blk_sz + 1);
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| 79 | xread(archive_handle->src_fd, buf, blk_sz);
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| 80 | archive_handle->offset += blk_sz;
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| 81 |
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| 82 | /* prevent bb_strtou from running off the buffer */
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| 83 | buf[sz] = '\0';
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| 84 |
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| 85 | while (sz != 0) {
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| 86 | char *end, *value;
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| 87 | unsigned len;
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| 88 |
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| 89 | /* Every record has this format: "LEN NAME=VALUE\n" */
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| 90 | len = bb_strtou(p, &end, 10);
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| 91 | /* expect errno to be EINVAL, because the character
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| 92 | * following the digits should be a space
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| 93 | */
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| 94 | p += len;
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| 95 | sz -= len;
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| 96 | if (
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| 97 | /** (int)sz < 0 - not good enough for huge malicious VALUE of 2^32-1 */
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| 98 | (int)(sz|len) < 0 /* this works */
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| 99 | || len == 0
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| 100 | || errno != EINVAL
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| 101 | || *end != ' '
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| 102 | ) {
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| 103 | bb_error_msg("malformed extended header, skipped");
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| 104 | // More verbose version:
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| 105 | //bb_error_msg("malformed extended header at %"OFF_FMT"d, skipped",
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| 106 | // archive_handle->offset - (sz + len));
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| 107 | break;
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| 108 | }
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| 109 | /* overwrite the terminating newline with NUL
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| 110 | * (we do not bother to check that it *was* a newline)
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| 111 | */
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| 112 | p[-1] = '\0';
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| 113 | value = end + 1;
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| 114 |
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| 115 | # if ENABLE_FEATURE_TAR_GNU_EXTENSIONS
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| 116 | if (!global && is_prefixed_with(value, "path=")) {
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| 117 | value += sizeof("path=") - 1;
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| 118 | free(archive_handle->tar__longname);
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| 119 | archive_handle->tar__longname = xstrdup(value);
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| 120 | continue;
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| 121 | }
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| 122 | # endif
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| 123 |
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| 124 | # if ENABLE_FEATURE_TAR_SELINUX
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| 125 | /* Scan for SELinux contexts, via "RHT.security.selinux" keyword.
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| 126 | * This is what Red Hat's patched version of tar uses.
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| 127 | */
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| 128 | # define SELINUX_CONTEXT_KEYWORD "RHT.security.selinux"
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| 129 | if (is_prefixed_with(value, SELINUX_CONTEXT_KEYWORD"=")) {
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| 130 | value += sizeof(SELINUX_CONTEXT_KEYWORD"=") - 1;
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| 131 | free(archive_handle->tar__sctx[global]);
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| 132 | archive_handle->tar__sctx[global] = xstrdup(value);
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| 133 | continue;
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| 134 | }
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| 135 | # endif
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| 136 | }
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| 137 |
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| 138 | free(buf);
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| 139 | #endif
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| 140 | }
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| 141 |
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| 142 | char FAST_FUNC get_header_tar(archive_handle_t *archive_handle)
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| 143 | {
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| 144 | file_header_t *file_header = archive_handle->file_header;
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| 145 | struct tar_header_t tar;
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| 146 | char *cp;
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| 147 | int i, sum_u, sum;
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| 148 | #if ENABLE_FEATURE_TAR_OLDSUN_COMPATIBILITY
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| 149 | int sum_s;
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| 150 | #endif
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| 151 | int parse_names;
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| 152 |
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| 153 | /* Our "private data" */
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| 154 | #if ENABLE_FEATURE_TAR_GNU_EXTENSIONS
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| 155 | # define p_longname (archive_handle->tar__longname)
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| 156 | # define p_linkname (archive_handle->tar__linkname)
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| 157 | #else
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| 158 | # define p_longname 0
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| 159 | # define p_linkname 0
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| 160 | #endif
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| 161 |
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| 162 | #if ENABLE_FEATURE_TAR_GNU_EXTENSIONS || ENABLE_FEATURE_TAR_SELINUX
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| 163 | again:
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| 164 | #endif
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| 165 | /* Align header */
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| 166 | data_align(archive_handle, 512);
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| 167 |
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| 168 | again_after_align:
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| 169 |
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| 170 | #if ENABLE_DESKTOP || ENABLE_FEATURE_TAR_AUTODETECT
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| 171 | /* to prevent misdetection of bz2 sig */
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| 172 | *(aliased_uint32_t*)&tar = 0;
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| 173 | i = full_read(archive_handle->src_fd, &tar, 512);
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| 174 | /* If GNU tar sees EOF in above read, it says:
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| 175 | * "tar: A lone zero block at N", where N = kilobyte
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| 176 | * where EOF was met (not EOF block, actual EOF!),
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| 177 | * and exits with EXIT_SUCCESS.
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| 178 | * We will mimic exit(EXIT_SUCCESS), although we will not mimic
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| 179 | * the message and we don't check whether we indeed
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| 180 | * saw zero block directly before this. */
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| 181 | if (i == 0) {
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| 182 | bb_error_msg("short read");
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| 183 | /* this merely signals end of archive, not exit(1): */
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| 184 | return EXIT_FAILURE;
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| 185 | }
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| 186 | if (i != 512) {
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| 187 | IF_FEATURE_TAR_AUTODETECT(goto autodetect;)
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| 188 | bb_error_msg_and_die("short read");
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| 189 | }
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| 190 |
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| 191 | #else
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| 192 | i = 512;
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| 193 | xread(archive_handle->src_fd, &tar, i);
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| 194 | #endif
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| 195 | archive_handle->offset += i;
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| 196 |
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| 197 | /* If there is no filename its an empty header */
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| 198 | if (tar.name[0] == 0 && tar.prefix[0] == 0) {
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| 199 | if (archive_handle->tar__end) {
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| 200 | /* Second consecutive empty header - end of archive.
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| 201 | * Read until the end to empty the pipe from gz or bz2
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| 202 | */
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| 203 | while (full_read(archive_handle->src_fd, &tar, 512) == 512)
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| 204 | continue;
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| 205 | return EXIT_FAILURE; /* "end of archive" */
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| 206 | }
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| 207 | archive_handle->tar__end = 1;
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| 208 | return EXIT_SUCCESS; /* "decoded one header" */
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| 209 | }
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| 210 | archive_handle->tar__end = 0;
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| 211 |
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| 212 | /* Check header has valid magic, "ustar" is for the proper tar,
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| 213 | * five NULs are for the old tar format */
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| 214 | if (!is_prefixed_with(tar.magic, "ustar")
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| 215 | && (!ENABLE_FEATURE_TAR_OLDGNU_COMPATIBILITY
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| 216 | || memcmp(tar.magic, "\0\0\0\0", 5) != 0)
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| 217 | ) {
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| 218 | #if ENABLE_FEATURE_TAR_AUTODETECT
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| 219 | autodetect:
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| 220 | /* Two different causes for lseek() != 0:
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| 221 | * unseekable fd (would like to support that too, but...),
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| 222 | * or not first block (false positive, it's not .gz/.bz2!) */
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| 223 | if (lseek(archive_handle->src_fd, -i, SEEK_CUR) != 0)
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| 224 | goto err;
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| 225 | if (setup_unzip_on_fd(archive_handle->src_fd, /*fail_if_not_compressed:*/ 0) != 0)
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| 226 | err:
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| 227 | bb_error_msg_and_die("invalid tar magic");
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| 228 | archive_handle->offset = 0;
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| 229 | goto again_after_align;
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| 230 | #endif
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| 231 | bb_error_msg_and_die("invalid tar magic");
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| 232 | }
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| 233 |
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| 234 | /* Do checksum on headers.
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| 235 | * POSIX says that checksum is done on unsigned bytes, but
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| 236 | * Sun and HP-UX gets it wrong... more details in
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| 237 | * GNU tar source. */
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| 238 | #if ENABLE_FEATURE_TAR_OLDSUN_COMPATIBILITY
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| 239 | sum_s = ' ' * sizeof(tar.chksum);
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| 240 | #endif
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| 241 | sum_u = ' ' * sizeof(tar.chksum);
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| 242 | for (i = 0; i < 148; i++) {
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| 243 | sum_u += ((unsigned char*)&tar)[i];
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| 244 | #if ENABLE_FEATURE_TAR_OLDSUN_COMPATIBILITY
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| 245 | sum_s += ((signed char*)&tar)[i];
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| 246 | #endif
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| 247 | }
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| 248 | for (i = 156; i < 512; i++) {
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| 249 | sum_u += ((unsigned char*)&tar)[i];
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| 250 | #if ENABLE_FEATURE_TAR_OLDSUN_COMPATIBILITY
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| 251 | sum_s += ((signed char*)&tar)[i];
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| 252 | #endif
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| 253 | }
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| 254 | /* This field does not need special treatment (getOctal) */
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| 255 | {
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| 256 | char *endp; /* gcc likes temp var for &endp */
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| 257 | sum = strtoul(tar.chksum, &endp, 8);
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| 258 | if ((*endp != '\0' && *endp != ' ')
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| 259 | || (sum_u != sum IF_FEATURE_TAR_OLDSUN_COMPATIBILITY(&& sum_s != sum))
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| 260 | ) {
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| 261 | bb_error_msg_and_die("invalid tar header checksum");
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| 262 | }
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| 263 | }
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| 264 | /* don't use xstrtoul, tar.chksum may have leading spaces */
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| 265 | sum = strtoul(tar.chksum, NULL, 8);
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| 266 | if (sum_u != sum IF_FEATURE_TAR_OLDSUN_COMPATIBILITY(&& sum_s != sum)) {
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| 267 | bb_error_msg_and_die("invalid tar header checksum");
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| 268 | }
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| 269 |
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| 270 | /* 0 is reserved for high perf file, treat as normal file */
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| 271 | if (!tar.typeflag) tar.typeflag = '0';
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| 272 | parse_names = (tar.typeflag >= '0' && tar.typeflag <= '7');
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| 273 |
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| 274 | /* getOctal trashes subsequent field, therefore we call it
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| 275 | * on fields in reverse order */
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| 276 | if (tar.devmajor[0]) {
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| 277 | char t = tar.prefix[0];
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| 278 | /* we trash prefix[0] here, but we DO need it later! */
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| 279 | unsigned minor = GET_OCTAL(tar.devminor);
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| 280 | unsigned major = GET_OCTAL(tar.devmajor);
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| 281 | file_header->device = makedev(major, minor);
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| 282 | tar.prefix[0] = t;
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| 283 | }
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| 284 | file_header->link_target = NULL;
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| 285 | if (!p_linkname && parse_names && tar.linkname[0]) {
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| 286 | file_header->link_target = xstrndup(tar.linkname, sizeof(tar.linkname));
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| 287 | /* FIXME: what if we have non-link object with link_target? */
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| 288 | /* Will link_target be free()ed? */
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| 289 | }
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| 290 | #if ENABLE_FEATURE_TAR_UNAME_GNAME
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| 291 | file_header->tar__uname = tar.uname[0] ? xstrndup(tar.uname, sizeof(tar.uname)) : NULL;
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| 292 | file_header->tar__gname = tar.gname[0] ? xstrndup(tar.gname, sizeof(tar.gname)) : NULL;
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| 293 | #endif
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| 294 | file_header->mtime = GET_OCTAL(tar.mtime);
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| 295 | file_header->size = GET_OCTAL(tar.size);
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| 296 | file_header->gid = GET_OCTAL(tar.gid);
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| 297 | file_header->uid = GET_OCTAL(tar.uid);
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| 298 | /* Set bits 0-11 of the files mode */
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| 299 | file_header->mode = 07777 & GET_OCTAL(tar.mode);
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| 300 |
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| 301 | file_header->name = NULL;
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| 302 | if (!p_longname && parse_names) {
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| 303 | /* we trash mode[0] here, it's ok */
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| 304 | //tar.name[sizeof(tar.name)] = '\0'; - gcc 4.3.0 would complain
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| 305 | tar.mode[0] = '\0';
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| 306 | if (tar.prefix[0]) {
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| 307 | /* and padding[0] */
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| 308 | //tar.prefix[sizeof(tar.prefix)] = '\0'; - gcc 4.3.0 would complain
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| 309 | tar.padding[0] = '\0';
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| 310 | file_header->name = concat_path_file(tar.prefix, tar.name);
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| 311 | } else
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| 312 | file_header->name = xstrdup(tar.name);
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| 313 | }
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| 314 |
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| 315 | /* Set bits 12-15 of the files mode */
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| 316 | /* (typeflag was not trashed because chksum does not use getOctal) */
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| 317 | switch (tar.typeflag) {
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| 318 | case '1': /* hardlink */
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| 319 | /* we mark hardlinks as regular files with zero size and a link name */
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| 320 | file_header->mode |= S_IFREG;
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| 321 | /* on size of link fields from star(4)
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| 322 | * ... For tar archives written by pre POSIX.1-1988
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| 323 | * implementations, the size field usually contains the size of
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| 324 | * the file and needs to be ignored as no data may follow this
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| 325 | * header type. For POSIX.1- 1988 compliant archives, the size
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| 326 | * field needs to be 0. For POSIX.1-2001 compliant archives,
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| 327 | * the size field may be non zero, indicating that file data is
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| 328 | * included in the archive.
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| 329 | * i.e; always assume this is zero for safety.
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| 330 | */
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| 331 | goto size0;
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| 332 | case '7':
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| 333 | /* case 0: */
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| 334 | case '0':
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| 335 | #if ENABLE_FEATURE_TAR_OLDGNU_COMPATIBILITY
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| 336 | if (last_char_is(file_header->name, '/')) {
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| 337 | goto set_dir;
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| 338 | }
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| 339 | #endif
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| 340 | file_header->mode |= S_IFREG;
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| 341 | break;
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| 342 | case '2':
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| 343 | file_header->mode |= S_IFLNK;
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| 344 | /* have seen tarballs with size field containing
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| 345 | * the size of the link target's name */
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| 346 | size0:
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| 347 | file_header->size = 0;
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| 348 | break;
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| 349 | case '3':
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| 350 | file_header->mode |= S_IFCHR;
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| 351 | goto size0; /* paranoia */
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| 352 | case '4':
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| 353 | file_header->mode |= S_IFBLK;
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| 354 | goto size0;
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| 355 | case '5':
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| 356 | IF_FEATURE_TAR_OLDGNU_COMPATIBILITY(set_dir:)
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| 357 | file_header->mode |= S_IFDIR;
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| 358 | goto size0;
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| 359 | case '6':
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| 360 | file_header->mode |= S_IFIFO;
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| 361 | goto size0;
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| 362 | case 'g': /* pax global header */
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| 363 | case 'x': { /* pax extended header */
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| 364 | if ((uoff_t)file_header->size > 0xfffff) /* paranoia */
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| 365 | goto skip_ext_hdr;
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| 366 | process_pax_hdr(archive_handle, file_header->size, (tar.typeflag == 'g'));
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| 367 | goto again_after_align;
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| 368 | #if ENABLE_FEATURE_TAR_GNU_EXTENSIONS
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| 369 | /* See http://www.gnu.org/software/tar/manual/html_node/Extensions.html */
|
|---|
| 370 | case 'L':
|
|---|
| 371 | /* free: paranoia: tar with several consecutive longnames */
|
|---|
| 372 | free(p_longname);
|
|---|
| 373 | /* For paranoia reasons we allocate extra NUL char */
|
|---|
| 374 | p_longname = xzalloc(file_header->size + 1);
|
|---|
| 375 | /* We read ASCIZ string, including NUL */
|
|---|
| 376 | xread(archive_handle->src_fd, p_longname, file_header->size);
|
|---|
| 377 | archive_handle->offset += file_header->size;
|
|---|
| 378 | /* return get_header_tar(archive_handle); */
|
|---|
| 379 | /* gcc 4.1.1 didn't optimize it into jump */
|
|---|
| 380 | /* so we will do it ourself, this also saves stack */
|
|---|
| 381 | goto again;
|
|---|
| 382 | case 'K':
|
|---|
| 383 | free(p_linkname);
|
|---|
| 384 | p_linkname = xzalloc(file_header->size + 1);
|
|---|
| 385 | xread(archive_handle->src_fd, p_linkname, file_header->size);
|
|---|
| 386 | archive_handle->offset += file_header->size;
|
|---|
| 387 | /* return get_header_tar(archive_handle); */
|
|---|
| 388 | goto again;
|
|---|
| 389 | /*
|
|---|
| 390 | * case 'S': // Sparse file
|
|---|
| 391 | * Was seen in the wild. Not supported (yet?).
|
|---|
| 392 | * See https://www.gnu.org/software/tar/manual/html_section/tar_92.html
|
|---|
| 393 | * for the format. (An "Old GNU Format" was seen, not PAX formats).
|
|---|
| 394 | */
|
|---|
| 395 | // case 'D': /* GNU dump dir */
|
|---|
| 396 | // case 'M': /* Continuation of multi volume archive */
|
|---|
| 397 | // case 'N': /* Old GNU for names > 100 characters */
|
|---|
| 398 | // case 'V': /* Volume header */
|
|---|
| 399 | #endif
|
|---|
| 400 | }
|
|---|
| 401 | skip_ext_hdr:
|
|---|
| 402 | {
|
|---|
| 403 | off_t sz;
|
|---|
| 404 | bb_error_msg("warning: skipping header '%c'", tar.typeflag);
|
|---|
| 405 | sz = (file_header->size + 511) & ~(off_t)511;
|
|---|
| 406 | archive_handle->offset += sz;
|
|---|
| 407 | sz >>= 9; /* sz /= 512 but w/o contortions for signed div */
|
|---|
| 408 | while (sz--)
|
|---|
| 409 | xread(archive_handle->src_fd, &tar, 512);
|
|---|
| 410 | /* return get_header_tar(archive_handle); */
|
|---|
| 411 | goto again_after_align;
|
|---|
| 412 | }
|
|---|
| 413 | default:
|
|---|
| 414 | bb_error_msg_and_die("unknown typeflag: 0x%x", tar.typeflag);
|
|---|
| 415 | }
|
|---|
| 416 |
|
|---|
| 417 | #if ENABLE_FEATURE_TAR_GNU_EXTENSIONS
|
|---|
| 418 | if (p_longname) {
|
|---|
| 419 | file_header->name = p_longname;
|
|---|
| 420 | p_longname = NULL;
|
|---|
| 421 | }
|
|---|
| 422 | if (p_linkname) {
|
|---|
| 423 | file_header->link_target = p_linkname;
|
|---|
| 424 | p_linkname = NULL;
|
|---|
| 425 | }
|
|---|
| 426 | #endif
|
|---|
| 427 |
|
|---|
| 428 | /* Everything up to and including last ".." component is stripped */
|
|---|
| 429 | overlapping_strcpy(file_header->name, strip_unsafe_prefix(file_header->name));
|
|---|
| 430 | //TODO: do the same for file_header->link_target?
|
|---|
| 431 |
|
|---|
| 432 | /* Strip trailing '/' in directories */
|
|---|
| 433 | /* Must be done after mode is set as '/' is used to check if it's a directory */
|
|---|
| 434 | cp = last_char_is(file_header->name, '/');
|
|---|
| 435 |
|
|---|
| 436 | if (archive_handle->filter(archive_handle) == EXIT_SUCCESS) {
|
|---|
| 437 | archive_handle->action_header(/*archive_handle->*/ file_header);
|
|---|
| 438 | /* Note that we kill the '/' only after action_header() */
|
|---|
| 439 | /* (like GNU tar 1.15.1: verbose mode outputs "dir/dir/") */
|
|---|
| 440 | if (cp)
|
|---|
| 441 | *cp = '\0';
|
|---|
| 442 | archive_handle->action_data(archive_handle);
|
|---|
| 443 | if (archive_handle->accept || archive_handle->reject
|
|---|
| 444 | || (archive_handle->ah_flags & ARCHIVE_REMEMBER_NAMES)
|
|---|
| 445 | ) {
|
|---|
| 446 | llist_add_to(&archive_handle->passed, file_header->name);
|
|---|
| 447 | } else /* Caller isn't interested in list of unpacked files */
|
|---|
| 448 | free(file_header->name);
|
|---|
| 449 | } else {
|
|---|
| 450 | data_skip(archive_handle);
|
|---|
| 451 | free(file_header->name);
|
|---|
| 452 | }
|
|---|
| 453 | archive_handle->offset += file_header->size;
|
|---|
| 454 |
|
|---|
| 455 | free(file_header->link_target);
|
|---|
| 456 | /* Do not free(file_header->name)!
|
|---|
| 457 | * It might be inserted in archive_handle->passed - see above */
|
|---|
| 458 | #if ENABLE_FEATURE_TAR_UNAME_GNAME
|
|---|
| 459 | free(file_header->tar__uname);
|
|---|
| 460 | free(file_header->tar__gname);
|
|---|
| 461 | #endif
|
|---|
| 462 | return EXIT_SUCCESS; /* "decoded one header" */
|
|---|
| 463 | }
|
|---|
